1. Field of the Invention
The present invention relates to a clutch engagement condition determining apparatus for a vehicle in which drive wheels are driven by an engine by way of a multi-staged transmission, and while the transmission is in operation in association with a gear shift lever operation thereof, the engine is disconnected from the transmission by means of a clutch whereas the drive wheels are driven by an electric motor, and a gearshift control apparatus utilizing the same determining apparatus.
2. Description of the Related Art
An engagement condition determining apparatus described in JP-A-11-69509 has conventionally been known as an engagement condition determining apparatus of the aforesaid type. The vehicle includes a multi-staged transmission for connecting an engine to a differential gear mechanism, a clutch for selectively bringing the multi-staged transmission into and out of engagement with the engine and an actuator for causing the clutch to switch between engaged and disengaged conditions. In addition, the engagement condition determining apparatus is adapted to determine whether the clutch is in an engaged condition or in a disengaged condition by detecting the stroke of the clutch. In this case, the detection of the stroke of the clutch is effected by detecting the traveling distance of the actuator by means of a sensor.
With the aforesaid conventional engagement condition determining apparatus, the sensor for detecting the traveling distance of the actuator is needed to determine whether the clutch is in the engaged or disengaged condition. Therefore, the sensor has to be accommodated within a narrow space such as in a transmission case and disposed near the clutch which tends to generate heat of high temperatures. Consequently, it becomes difficult to secure a space where the sensor is installed and to obtain the wiring of the sensor properly, and the sensor is required to be provided with a certain degree of heat resistance. As a result, this results in increase in production cost.
The invention was made with a view to solving the problem, and an object thereof is to provide a vehicle clutch engagement condition determining apparatus which can properly determine whether the clutch is in an engaged condition or a disengaged condition without employing an exclusive detecting device such as a sensor and reduce the production costs and a gearshift control apparatus employing the same engagement condition determining apparatus.
With a view to attaining the object, according to a first aspect of the invention, there is provided a vehicle clutch 5 engagement condition determining apparatus 1 for a vehicle in which drive wheels 4 are driven by an engine 2 by way of a multi-staged transmission 10, the transmission 10 is actuated in association with the operation of a gear shift of the transmission 10, and while the transmission 10 is in operation the engine 2 is disconnected from the transmission 10 by means of a clutch 5 whereas the drive wheels 4 are driven by an electric motor 3, the automobile clutch 5 engagement condition determining apparatus 1 comprising a vehicle speed parameter detecting means (a motor speed sensor 36, an ECU 40, steps 4, 6) for detecting a vehicle speed parameter (motor speed NM, motor speed corresponding value NMCAL) representing the speed status of the vehicle, a gear shift operation detecting means (a shift position sensor 37, ECU 40, step 2) for detecting whether of not the gear shift operation has been executed, a target vehicle speed parameter setting means (ECU 40, step 5) for setting a target vehicle speed parameter (a target speed NOBJ) based on a vehicle speed parameter (motor speed corresponding value NMCAL) detected by the vehicle speed parameter detecting means when the execution of the gear shift operation is detected by the gear shift operation detecting means (when the result of determination in step 2 is YES), a control signal value determining means (ECU 40, steps 6, 7) for determining a control signal value (a control current value I) for controlling the revolution of the electric motor 3 so that the detected vehicle speed parameter (motor speed NM) matches a target vehicle speed parameter (a target speed NOBJ) set by the target vehicle speed parameter setting means while the drive wheels 4 are driven by the electric motor 3, a varying condition detecting means (ECU 40, step 8) for detecting the varying condition (an electric current value deviation DI) of a control signal value determined by the control signal value detecting means, and an engagement condition determining means (ECU 40, steps 11 to 15) for determining the engagement condition of the clutch 5 according to the varying condition (the electric current value deviation ID) of a control signal value detected by the varying condition detecting means.
According to the automobile clutch engagement condition detecting apparatus, the rotating condition of the drive wheels is detected, so that whether or not the gear shift operation has been effected is detected, and when it is detected that the gear shift operation has been executed the target vehicle speed parameter is set based on the detected vehicle speed parameter. Furthermore, the control signal value for controlling the rotation of the electric motor is determined so that the detected vehicle speed parameter matches the target vehicle speed parameter while the drive wheels are driven by the electric motor, and the varying condition of the control signal value is detected. Then, the engagement condition of the clutch is determined according to the detected varying condition of the control signal value.
Thus, when the transmission operates in association with the operation of the gear shift thereof, the control signal value of the electric motor is set such that the vehicle speed parameter matches the target vehicle speed parameter determined based on the vehicle speed parameter when the gear shift operation is executed. Consequently, even if the driving force of the engine that is conveyed to the drive wheels is reduced due to the clutch switching from the engaged condition to the disengaged condition in association with the start of operation of the transmission, since the control signal value of the electric motor is controlled as described above, the speed status of the vehicle is maintained so as not to alter. Owing to this, the engagement condition of the clutch is reflected on the varying condition of the control signal value of the electric motor and therefore the engagement condition of the clutch while the transmission is in operation can properly be determined according to the results of detection of varying conditions, whereby differently from the conventional example, the necessity is obviated of the exclusive sensor for detecting the traveling distance of the actuator. This results in omission of the sensor and work involved in getting the sensor wired properly, whereby the production costs can be reduced. In addition, since there is no need to secure a space for installation of the sensor, the transmission case incorporating therein the cutch and the transmission itself can be made compact (note that when references are made to the xe2x80x9cdetection of a vehicle speed parameterxe2x80x9d and xe2x80x9cdetection of a control signal valuexe2x80x9d in this specification the xe2x80x9cdetectionxe2x80x9d is not limited to a direct detection by a sensor but may include the estimation through calculation).
According to a second aspect of the invention, there is provided a vehicle clutch 5 engagement condition determining apparatus 1 as set forth in the first aspect of the invention, wherein the vehicle speed parameter is either of a vehicle speed and a vehicle acceleration.
According to the automotive clutch engagement condition determining apparatus, since the control signal value of the electric motor is set so that the vehicle speed or vehicle acceleration matches the target vehicle speed or target vehicle acceleration determined based on the vehicle speed or vehicle acceleration when the gear shift operation is executed, the vehicle speed or vehicle acceleration is maintained so as not to change while the transmission is in operation. Consequently, as has been described above, the engagement condition of the clutch can properly be determined according to the varying condition of the control signal value of the electric motor.
According a third aspect of the invention, there is provided a gearshift control apparatus 41 comprising a vehicle clutch 5 engagement condition determining apparatus 1 as set forth in the first aspect of the invention a transmission driving means (first to fifth speed actuators 31 to 33) for driving the transmission 10 and a gear shift control means (ECU 40) for shifting gear stages of the transmission 10 by controlling the transmission driving means when the clutch 5 is determined as being in a disengaged condition (when the results of determination in steps 11 to 13 are YES) by the engagement condition determining means.
According to the gearshift control apparatus, when the clutch is determined as being in the disengaged condition by the engagement condition determination apparatus as set forth in claim 1, the gear stages or gear ratio steps of the transmission are changed. Namely, the gear stages of the transmission can be changed at appropriate timings based on the results of determination of the engagement condition of the clutch by the engagement condition determining apparatus.